Preparation of cortisone compounds and prednisone compounds

ABSTRACT

Delta 4-3,11,20-Triketo steroids are iodinated in the presence of azobisisobutyronitrile to produce a mixture of unstable iodides, and the latter are treated with acylolysis reagents to produce a substantial fraction of Delta 1,4-3,11,20-triketo-21acyloxy products.

United States Patent 1 3,699,136 Huber [451 Oct. 17, 1972 [54] PREPARATION OF CORTISONE OTHER PUBLICATIONS COMPOUNDS AND PREDNISONE COMPOUNDS [72] Inventor: Joel E. Huber, Kalamazoo, Mich. [731 Assignee: The Upjohn Company, Kalamazoo,

Mich.

[22] Filed: Jan. 6, 1972 [21] Appl. No.: 215,918

[52] US. Cl ..260/397.45 [51] Int. Cl ..C07c 169/34 [5 8] Field of Search ..lMachine Searched Steroids [56] References Cited UNITED STATES PATENTS 3,104,246 9/1963 Amiard et al ..260/397.45

Rothman et al., J. Org. Chem. 25 p. 1966- 1968 (1960).

Primary Examiner-Henry A. French Attorney-John Kekich et al.

57 ABSTRACT A-3,l 1,20-Triketo steroids are iodinated in the presence of azobisisobutyronitrile to produce a mixture of unstable iodides, and the latter are treated with acylolysis reagents to produce a substantial fraction of A --3,l 1,20-triketo-2l-acyloxy products.

4 Claims, No Drawings PREPARATION OF CORTISONE COMPOUNDS AND PREDNISONE COMPOUNDS BACKGROUND OF THE INVENTION Chem., 25, pages 1966458).

The iodination of certain kinds of steroids that contain an unsubstituted 2l-carbon to produce a 2l-diiodo product is described in U. S. Pat. No. 3,104,246 particularly with respect to the production of 2l-diiodol6B-methy1-A" -pregnatriene- 1 7a-0I-3,20-dione. This 'diiodo product is then treated with acetic acid and potassium acetate in the presence of dimethylforrnamide to produce corresponding 2l-acetoxy compound. See Step H of the patent.

SUMMARY OF THE INVENTION I have discovered that the known iodination conditions (I), such as described above in the acknowledged prior art, when applied to aA-3,ll,20-triketo steroid having an unsubstituted 2l-carbon atom, in the presence of azobisisobutyronitrile, yields a mixture of unstable iodides which can be treated directly (2) with the acylolysis reagents described above and more particularly below to produce a mixture of 2l-acylated steroids corresponding in structural character to the starting material with the exception of the introduced 21- acyloxy group and with the further surprising exception of a substantial fraction n the mixture having an introduced A -bond.

Thus, for example, I can produce prednisone in substantial quantities by applying the successive steps of (l )and 2) to l7a-hydroxy-4-pregnene-3,1 1,20-trione.

The reaction of this invention can be applied to any starting material having the fundamental A-3,l1,20- triketo-pregnene structural characteristic, and the result will be the corresponding 2l-acylate product mixture of A and A steroids.

The above reaction can be shown as follows:

Mixture of iodo compounds are H, methyl or fluoro, M is an alkali metal and Alk is an alkyl group of from one to four carbon atoms. I

The (S -3,1 1,20-triketo .pregnene starting material can be one which contains substituent groups such as the 6-methyl, the l6-methyl, and the like which do not take part in either of reactions (1') or (2),

Step (I), the iodination, can be carried out in an inert reaction medium in the presence of an inorganic base such as calcium hydroxide, magnesium hydroxide, or sodium carbonate. The iodine can be added in solution, and the reaction takes place at room temperature or above, and preferably below the boiling point of the mixture.

Step (2) can be carried out by taking the iodinate product l) with or without purificatiomdissolved in an inert reaction medium and subjecting it to reaction with a hydrocarbon carboxylic acid such as acetic acid,

'propionic acid, Valeric acid, isovaleric acid, trimethyl acetic (pivalic) acid, hexanoic acid, diethylacetic, cyclopentylacetic, benzoic, ethylbenzoic, succinic acid and the like in the presence of a trialkylamine, e.g., v

starting steroid material, and the quantity of iodine used in (1) can be from 2 to 4 moles per mole of starting steroid material. The amount of carboxylic acid and trialkyl amine, with respect to each other can vary from 0.5 to 2.0 molar proportions, and the amount of carboxylic acid can vary from a molar amount up to twice a molar amount based upon the quantity of steroid in the reaction mixture.

Step (2) can be carried out using an alkali metal salt of the carboxylic acid in place of the acid/amine mixture noted above. When the salt, e.g., potassium carboxylate, is used it is conveniently added to the reaction mixture in the form of a solution in an inert solvent as acetone.

, acid/trimethylamine mixture of Example 1.

product is .a mixture of cortisone 21- pivalate andprednisone21-pivalate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preparation of Cortisone Acetate and Prednisone Acetate To a solution of 1.0 g. of 17a-hydroxy-4-pregnene- 3,1 1,20-trione in 20 ml. of dry methanol was added 1.0 g. of finely powdered calcium oxide and 100 mg. of azobisisobutyronitrile. The temperature was adjusted to 25 and a solution of 2.25 g. of iodine in 3.5 ml. of dry methanol and 5 ml. of dry tetrahydrofuran was Example 1 added dropwise with stirring overa 70 minute period.

After stirring for an additional minutes, the reaction mixture was filtered to remove the unreacted calcium.

oxide. The solids were washed with methylene chloride and the combined wash and filtrate was added to 200 ml. of benzene. This was washed with 50 ml. of sodium thiosulfate, 25 ml. of saturated sodium bi-carbonate and several portions of water.

The benzene layer was concentrated in vacuo to dryness and the residue was dissolved in ml. of acetone. This was added to a solution of 5 ml. of glacial acetic acid and 7 ml. of triethyl amine in 15 ml. of acetone 7 and .was heated. at reflux for 1.5 hours. The dark reaction mixture was added to 200 ml. of benzene and this was washed thoroughly with water. The organic layer and whereinR isthe acyl radicalof a hydrocarbon carboxwas concentrated in vacuo to dryness and the high boilj ing residue was chromatographed on a 150 g. silica gel column. The column was developed with 1 percent methanol in chloroform, and 100 ml. fractions were ane, C 1.05); UV max (95% EtOH) 239 nm (15,200).

Example 2 The process of Example 1 can be repeated substituting potassium 'pivalate for the The The substitution of a-fluorocortisone in the process of Example 1 yields a mixture of a-fluorocortisone 21- acetate and 6a-fluoro prednisone 21-acetate.

The substitution of 6-methyl or 16-methyl cortisone in the process of Example 1 results in a mixture of the corresponding 6-methyl or 16-methyl cortisone. acetates and 6-methyl or 16-methyl prednisone acetates.

lclaim:

l. A method for producing a mixture of compounds of the following structural formulas:

acetic ylic acid of from two to 12 carbon atoms, and R and R I are H, methyl or fluoro, which comprises subjecting a wherein R and R, are as defined above, to iodination by reaction with iodine in thepresent of an inorganic base and azobisisobutyronitrile to produce a mixture of unstable iodo compounds and reacting the latter with a member of the group consisting of a mixture of a a hydrocarbon carboxylic acid from one to 12 carbon atoms, with a trialkyl amine in which the alkyl group is from one to four carbon atoms, and an alkali metal salt of a hydrocarbon carboxylic acid from one to 12 carbon atoms, to effect 21-acyloxylation and substantial 1- dehydrogenation of the starting material.

2. The method of claim. 1 in which the hydrocarbon carboxylic acid in either alternative is acetic acid.

3. The method of claim 1 in which the hydrocarbon carboxylic acid in either alternative is pivalic acid.

4.- The method according to claim 1 for producing a mixture of cortisone acetate and prednisone acetate which comprises reacting 17a-hydroxy-4-pregnen- 3,11,20-trione with about a v2-molar proportion of iodine in'the presence of calcium oxide and azobisisobutyronitrile, removing unreacted calcium oxide from the reaction mixture and separating water solubles therefrom; reacting the iodinated product in solution with glacial acetic acid and triethylamine until completion of the reaction, and recovering from the reaction mixture cortisone 21-acetate and prednisone 21-acetate. 

2. The method of claim 1 in which the hydrocarbon carboxylic acid in either alternative is acetic acid.
 3. The method of claim 1 in which the hydrocarbon carboxylic acid in either alternative is pivalic acid.
 4. The method according to claim 1 for producing a mixture of cortisone acetate and prednisone acetate which comprises reacting 17 Alpha -hydroxy-4-pregnen-3,11,20-trione with about a 2-molar proportion of iodine in the presence of calcium oxide and azobisisobutyronitrile, removing unreacted calcium oxide from the reaction mixture and separating water solubles therefrom; reacting the iodinated product in solution with glacial acetic acid and triethylamine until completion of the reaction, and recovering from the reaction mixture cortisone 21-acetate and prednisone 21-acetate. 